Table 2

Predicted PXR EC50 data for molecules with published -fold activation values obtained from CV-1 cells or Caco-2 cells expressing the human PXR plasmid and a chloramphenicol acetyltransferase reporter plasmid

MoleculeCatalyst Predicted EC50Observed PXR Activation/DeactivationReference
μM
Ecteinascidin0.342-a IC50approx. 3 nM2-b Synold et al., 2001
Troglitazone0.472-a 7-fold2-b Jones et al., 2000
LGD1069 (targretin)0.572-a 4-fold Jones et al., 2000
Nifedipine0.582-a 10-fold2-b Bertilsson et al., 1998
5–10-fold Blumberg et al., 1998
Dexamethasone-t-butylacetate0.662-a >5–<10-fold2-b Lehmann et al., 1998
Docetaxel (Taxotere)1.2None Synold et al., 2001
Paclitaxel (Taxol)1.4EC50 approx. 5 μM Synold et al., 2001
Lovastatin1.5≈5-fold Lehmann et al., 1998
Phenobarbital13>17-fold at 1 mM Jones et al., 2000
≈5-fold Lehmann et al., 1998
Trans-nonachlor5.5≈6-fold Jones et al., 2000
≈4-fold Lehmann et al., 1998
Cortisol7.1≈3-fold Bertilsson et al., 1998
≈4-fold Blumberg et al., 1998
Corticosterone8.612-fold Blumberg et al., 1998
3-fold Jones et al., 2000
Hypericin3.1≈1.5-fold Moore et al., 2000a
Cholesterol4.3≈1.5-fold Bertilsson et al., 1998
≈1-fold Kliewer et al., 1998
Progesterone5.9≈4-fold Lehmann et al., 1998
≈5-fold Kliewer et al., 1998
≈4-fold Blumberg et al., 1998
Aldosterone6.5≈1-fold Bertilsson et al., 1998
Spironolactone6.5≈5-fold Lehmann et al., 1998
≈3-fold Jones et al., 2000
≈3-fold Blumberg et al., 1998
Rutin7≈2-fold Moore et al., 2000a
Pregnenolone7.4≈3-fold Bertilsson et al., 1998
≈5-fold Lehmann et al., 1998
≈7.5-fold Kliewer et al., 1998
≈2-fold Jones et al., 2000
≈3-fold Blumberg et al., 1998
Metyrapone9.4≈4-fold Wright 1999
17α-Hydroxyprogesterone11≈1.5-fold Jones et al., 2000
Cortisone14None Jones et al., 2000
Dihydrotestosterone14≈1.5-fold Jones et al., 2000
≈5-fold Blumberg et al., 1998
Estradiol26≈3-fold Jones et al., 2000
Scopoletin120≈1.5-fold Moore et al., 2000a
Quercetin300≈1.5-fold Moore et al., 2000a
Kaempferol380≈1-fold Moore et al., 2000a
Myricetin15000≈1.5-fold Moore et al., 2000a

Cell extracts were assayed for chloramphenicol acetyltransferase activity compared to controls, as described in the original references.

  • ≈, approximate -fold activation/deactivation.

  • 2-a  Potent ligand predicted EC50 < 1 μM.

  • 2-b  Potent ligand observed >5-fold activation of PXR.